Roll and pitch suppressor for floating marine structures

ABSTRACT

A roll and/or pitch suppressor for floating marine structures is disclosed in which pairs of buckets are suspended from outriggers symmetrically arranged in relation to a roll or pitch axis. The buckets of a pair fill during down stroke and empty during up stroke in phase opposition to provide roll or pitch suppressing or damping momentum.

O Unlted States Patent 11113,568,620

[72] Inventor Donald W. Douglas [56] References Cited 3 27: RM Rollins "ills, Calif- UNITED STATES PATENTS I 1,709,219 4/1929 Hi1le.., 114/123 gm- 22512 3,064,613 11/1962 Hubick 114/121 I [45] Patented Mar. 9, 1971 .Primary Examiner-Trygve M. Blix Continuation-impart of application Ser. No. Attorney-myth, R0810" Pavitt 693,238, Dec. 26, 1967 1311 6 9. T T [54] ROLL AND PITCH SUPPRESSOR FOR FLOATING MARINE STRUCTURES ABSTRACT- A TO and/or p1tch suppressor for floatmg 24 Claims Drawing Flgs' marine structures is disclosed in which pairs of buckets are [52] US. Cl 114/125 suspended from outriggers symmetrically arranged in relation [51] Int. Cl B63b 43/06 to a roll or pitch axis. The buckets of a pair fill during down [50] Field of Search 1 14/121, stroke and empty during up stroke in phase opposition to pro-- 123, 125 vide roll or pitch suppressing or damping momentum.

PATENTED MAR 9 I971 SHEET 1 OF 7 PATENTED MAR 9 I97! SHEET 2 [IF 7 PATENTED MAR 9191: 3 5 8 520 sum 3 or 7.

RULL AND FITCH SUPPRESSUR FOR FLOATW MAlIilNlE STRUCTUlRlEfl This application is a continuation-in-part of my application, Ser. No. 693,238, filed Dec. 26, 1967 and now abandoned. My application Ser. No. 724,924, filed Apr. 29, 1968 and now abandoned relates to a control device usable in conjunction with structures disclosed in the parent and in the present application.

The present invention relates to a stabilizing and roll and pitch suppressing or clamping device for floating marine structures, such as boats, barges, floating platforms, etc. Floating platforms or moored barges are used, e.g., for offshore drilling, ocean bottom mining, or the like. They can be regarded as small, floating artificial islands; even though they are, to some extent, connected to the bottom of the sea as required for the mining or drilling operation, the structures are maintained above the water level by flotation and buoyan cy. Therefore, such a structure is forced to follow motions of the surface of the sea and will, to some extent, ride on waves. As a consequence the floating structure undergoes rolling and pitching motion. As this is detrimental to the operations to be performed on and from the platform or barge, it is advisable to provide structure for suppressing or at least damping such roll and pitch.

Numerous systems and devices have been suggested, especially for ships, for damping the roll thereof. These devices can be classified roughly in two groups. One group uses subsurface hydrofoils or the like for stabilizing the position of the boat. Operation of such hydrofoils requires motion of the boat along the roll axis. Thus, hydrofoils are, per se, not usable for stabilizing a floating but otherwise immobile marine structure.

The other group of stabilizers uses tanks in the interior of a boat and in which by one means or another, liquid is caused to move in phase opposition to the rolling motion. The tank thus provides a sequence of alternatingly oriented momenta, tending to stabilize the boat in relation to the roll axis. Devices of this type require either auxiliary power for pumping the liquid back and forth or they make use of resonance, i.e., the liquid in the stabilizing tank is tuned to oscillate at the frequency equal to the normal roll frequency of the floating structure but in phase opposition thereto. Such a device, however, requires considerable amounts of liquid if the momenta thus developed are to have noticeable effect. The pumping power required is considerable and reliance on the resonance phenomenon is not satisfactory. The effective momentum developed for roll suppression is rather low considering the large quantities of liquid required.

The present invention relates to a roll and pitch suppressing or damping device requiring very little auxiliary power and no auxiliary liquid, i.e., the inventive device is not an internally closed system; a simplified version of the preferred embodiment of the invention does not require any power at all.

it should be mentioned that the terminology roll and pitch of a marine vehicle is used to define angular motion respectively about a nonvertical axis. The roll axis extends in the direction of propagating motion of the vehicle and the pitch is any angular motion about an axis extending perpendicular to the roll axis and horizontally for zero roll. A floating marine structure has no direction of propagation; thus, the term roll" shall be used to define angular oscillations rotating about any nonvertical axis running through the marine structure.

in accordance with the preferred embodiment of the present invention, outriggers extend from the floating structure to be stabilized and buckets are suspended from the Outriggers. Preferably, though not necessarily, buckets and Outriggers are arranged in pairs and placed symmetrically in relation to axes of preferred roll. Since any angular motion about any horizontal axis can be defined by angular motions about two horizontal and transverse axes, an arrangement of four buckets and four Outriggers suffices for the general case, arranged respectively symmetrically relative to two perpendicular axes. Additional buckets and Outriggers may be needed only for reasons of construction. It may be of advantage to use two smaller buckets in lieu of one large one.

A bucket dips into the sea as a result of the rolling motion and is partially or fully submerged, i.e., it may sink beneath the surface of the sea, depending on the severity of the roll. During that phase the bucket is filled with water through suitable openings from the surrounding sea. It is preferred that the bucket remain empty untiLhaving reached the low point of its downward motion so that the buoyancy of the empty bucket, when being forced into the water by the roll, already provides antiroll torque. As the rolling reverses, the bucket now filled with water is lifted out of the sea. As the water-filled bucket is lifted, it provides a momentum tending to counteract the roll. That momentum is approximately proportional to the distance of the bucket suspension from the center of the structure times the weight of the water in the bucket.

The lifted bucket, in general, is now to remain water-filled as long as the roll-producing momentum has a direction opposite to the stabilizing momentum exerted by the water-filled bucket upon the marine structure. Thus, during most of the up stroke of the bucket it should remain full. As rolling reverses, the bucket must be emptied, at the latest by the time the return or down stroke of the bucket commences.

In the preferred form of practicing the invention, the bucket is maintained full during most of the up stroke so that the sta bilizing momentum is effective in full throughout that period. However, shortly before reaching uppermost position the bucket is emptied, possibly rather rapidly, by providing outflow over a large cross-sectional area. The bucket is filled during each down stroke. Suitable valves or openings open as the bucket sinks. The valves close at about the time an up stroke begins.

It follows, therefore, that a pair of buckets symmetrically disposed to a roll axis operate preferably anticyclic. As one moves up, the other one moves down. The one moving up is full, the one moving down is empty. Preferably control is exerted such that the one moving up remains full throughout the up stroke, the one moving down remains empty throughout the down stroke. Thus, both buckets exert antiroll action upon the structure from which they extend. At the end of the roll phase the full bucket has highest position out of the water, the empty bucket has lowest (deepest) position in the water. At that point, valves open for both buckets, discharging the full one, filling the empty one. As the rolling motion reverses direction, the previously empty bucket is now filled when beginning to move up, the previously full one is now empty when beginning to move down. Thus, antiroll action has likewise reversed direction.

Auxiliary power is required merely for the control of the outflow if outflow is to be prevented during most of the up stroke but to be completed before beginning of the down stroke. Even that control can be dispensed with, in a simplified form of the invention, if water can discharge from the bucket throughout the up stroke. The discharge is to be completed by the time the roll reverses phase, but the outflow is restricted to an extent still permitting lifting of a substantial amount of water by the bucket out of the sea. However, controlled inflow and outflow at the time a bucket reverses direction of motion is preferred to obtain optimum results.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. 1 illustrates a top view of a floating marine structure improved for roll suppression in accordance with the present invention;

FIG. 2 illustrates a side elevation of the structure shown in FIG. 2;

FIG. 3 illustrates an elevation of a single outrigger with bucket in operating as well as in retracted position;

FIGS. la, 2a and 3a illustrate views analogous to FIGS. l, 2 and 3 of a boat improved for roll suppression in accordance with the present invention;

FIG. 4 is a top view of the outrigger in operating position as shown in FIG. 3;

FIG. 5 shows a side view of a bucket used for suspension from an outrigger as shown in FIG. 3;

FIG. 5a illustrates a detail of FIG. 5;

FIG. 6 is a perspective view of the bucket shown in FIG. 5;

FIG. 7 is a perspective view of the bottom of the bucket shown in FIG. 6;

FIG. 7a shows a detail of the bottom frame of the bucket shown in FIGS. 6 and 7; and

FIGS. 8 and 9 are respectively side and front elevations of a control device for controlling the emptying of buckets as shown in FIG. 3 and others.

Turning now to the detailed description of the drawings, FIGS. 1 and 2 thereof, are respectively top and plan view of a floating marine structure, such as a moored barge 10, improved with regard to roll and pitch stabilization in accordance with the present invention. The barge 10 may serve as a floating platform for ocean bottom mining or the like, and is representatively shown to have rectangular configuration, which is of no consequence in principle. Nevertheless, the barge will roll about a horizontal axis which runs through the center of the barge, parallel to the long side of the rectangle, and the barge will pitch about a horizontal axis running through the center of the barge parallel to the short side of the rectangle; as roll and pitch combine, the barge will undergo angular motion at any instant about any horizontal axis. The roll and pitch periods are expected to differ so that the position of the instantaneous axis of combined roll and pitch varies. However, roll and pitch periods each are essentially constant, so that the axis of combined roll and pitch changes position periodically.

The improvement in accordance with the invention tends to stabilize the position of the barge and platform 10 with regard to its tendency to roll about any horizontal axis, hereafter called roll axis generally, regardless of the instantaneous orientation thereof; moreover the inventive improvement in its preferred form tends to stabilize the barge regardless of any variations in time of this instantaneous roll axis. However, the construction could be simplified if rolling and/or and/or pitching occurs about particular, fixed axis as a preferred interference with the normal and desired horizontal position of the barge 10. This is particularly so if the invention is employed to stabilize a boat about its roll axis when anchored; little pitch is expected to occur in this situation.

As illustrated, there are four outriggers a, 20b, 20cand 20:1, for respectively suspending buckets such as 30a, 30b, 30c and 30d. While not essential in principle the buckets are grouped in pairs, with outriggers 20a and 20c being arranged symmetrically to the roll axis proper of the particular barge 10, and outriggers 20b and 20d are arranged symmetrically to the pitch axis. For a calm sea and for a horizontal position of the platform, the buckets are suspended so that they are at least partially submerged. In order to obtain a stabilizing effect even for small amplitude roll, submergence for half a bucket height as zero" position and as illustrated in FIG. 3, is preferred.

Barge 10 has a centrally located mast 11 from the top of which run suspension cables 12a, 12b, 12c and 12d respectively to the outriggers 30a through 30d. These cables may be similar to tackles for sails, running over pulleys on top of the mast and back to a winch 1.3. As the winch 13 winds the cables 12a, etc., on a drum the outriggers are folded up when not needed. The mast has a central location for reasons of symmetry; such symmetry, however, is not essential. Moreover, if the barge has a structure such as a drilling derrick or the like, such structure may well serve for guiding the suspension of the outriggers.

As will be explained more fully below, the buckets will dip deeper into the sea and be lifted therefrom in alternating sequence as a result of the roll. This necessitates emptying the buckets in timed relation to the roll cycle. In the preferred form of practicing the invention, the buckets should be filled also in timed relation to the roll cycle, preferably such that a bucket is permitted to fill at the time the respective symmetrically positioned other bucket of a pair discharges. A centrally located control section 50 selectively opens the buckets for individually timing the discharge thereof, particularly after having been lifted out of the water. Control section 50 is linked with the buckets through control cables such as 15a, 15b, etc., in a manner more fully explained below.

FIGS. 1a and 2a illustrate a somewhat different environment for practicing the invention, but in accordance with similar principles. A boat is provided with a pair of outriggers a and 12Gb from which are suspended streamlined buckets a and 1311b respectively, when the outriggers are swung out as shown.

FIGS. 3 and 4 illustrate the outrigger and the suspension structure for single bucket in greater detail. Outrigger and bucket are respectively denoted hereby merely by numerals 20 and 30, and it is understood that this construction is similar for all four outriggers and buckets. The lettering a, -b, -c and a' will be used in the following only if the different outrigger-bucket systems and their control require such distinction.

The outrigger 20 is constructed as an A-frame 21, the apex of which is held by and suspended from the cable 12. A bracing cable 27 prevents the A-frame 21 from pivoting in up direction, which is counterclockwise in the plane of FIG. 3. Upon removal or slackening of bracing cable 27, A-frame 21 can be pivoted up by means of two hinges 22. The cable 27 is fastened to a fastener block 23 which, for example, may be attached to and released from the hull of the structure 10.

A boom 24 projects from the apex point of A-frame 21 and is secured thereto. A suspension rod or tube 32 is pivotally linked also to the apex point of A-frame 21. The bucket 30 is suspended by the tube 32 and the latter is in particular affixed and secured to the bottom 31 of the bucket. Bracing cables 25 and 26 are respectively attached to the hull of barge 10 and to the end point of the boom 24 to hold the tube 32 in vertical position, for normal, stabilized position of the barge. The brace cables 25 and 26 in particular will prevent the tube 32 with bucket 30 from oscillatorily swinging around the point of suspension of the tube 32 at the apex of A-frame 21. Bracing cable 27 prevents the bucket from pushing tube 32 and frame 21 in up direction when hitting sea level.

The bucket structure and its immediate suspension system is illustrated in greater detail in FIGS. 5 and 6 with alternative structure being shown in FIGS. 7 and 7a. The bucket 30 has a cylindrical, tubular wall 33 reinforced by rings 331, 332 and 333. Wall 33 with bottom ring 333 is normally seated on the bottom 31 of the bucket. A pair of spiders 341 and 342 support centrally located bushings 351 and 352 respectively and they provide bracing for the cylindrical wall 33, respectively at rings 331 and 332. The bushings can slide on and over tube 32 so that wall 33 of the bucket can move axially along the tube. A pair of short arms 353 and 354 extend radially from bushings 351 and 352 respectively, and in vertical alignment to each other. The arms 353 and 354 have vertically aligned apertures which receive a vertically oriented control rod 36. The control rod 36 is anchored to the arms and terminates at its upper end in a hook 361. The end ofcontrol cable 15 is tied to hook for suspending the control rod 36. The control cable 15 runs over a guide pulley 323 on top of rod or tube 32 to change the direction of the cable from the vertical to essentially a horizontal direction and towards the control section 50 on the platform on barge 10.

It will be appreciated that the cylindrical wall 33 of the bucket is suspended from cable 15 by cooperation of rod 36, arms 353, 354, bushings 351, 352 and spiders 341, In order to prevent rotation of wall 33 of the bucket around its center axis, which is also the axis of rod or tube 32, a short guide arm 321 with an aperture 322 extends radially from the tube 32 in between the two bushings 351 and 352. The control rod 36 passes through and is slidingly received by the aperture 322.

Bucket wall 33 can be lifted from the bottom 31 by means of cable whereby bushings 351 and 352 guide the wall lifting and restrict any motion of the bucket wall to progressively variable positions in axial direction along tube 32. Bushing 352 serves as a stop for defining maximum lifting of the bucket wall from bottom 31, when the bushing abuts arm 321. Any rotary motion of the wall 33 is inhibited also by arm 321 guiding control rod 36.

in one form of practicing the invention, the bottom 31 of the bucket is solid so that water flows in and out of the bucket only by lifting wall structure 33 from bottom 31. However, FIGS. 7 and 7a show an alternative bottom structure. The bottom of the bucket is constructed to include a ring 311 as well as a central structure 312 to which is fastened tube 32. The ring 311 is connected to the central structure 312 by means of six spokes 313, thereby defining a spoke wheel-type bottom frame. A set of six braces 314 interconnect respectively adjacent spokes 313. The six braces 314 define a hexagon type configuration lending additional structural stability to the bucket bottom frame.

A pair of hinges, such as 315, is mounted to each of the spokes 313. As illustrated in FIG. 7, a sector-shaped valve plate 316 is connected to each hinge pair, there are altogether six of such valve plates accordingly. Each valve plate 316 is particularly secured with one of its radially extending edges to the two respectively associated hinges 315 on a spoke. The other radially extending edge of each valve plate 316 rests on the respective next spoke, if the valve is closed. Thus, as one can see best in FIG. 7a, each spoke serves, on the one hand, for supporting a pair of hinges to which is linked a valve plate; on the other hand, the same spoke serves as a seat for the neighboring valve plate (here denoted with 316') when closed.

It will be appreciated that each of the six valves can open when pressure is exerted upon the respective valve plates from below, while they close if there is pressure from above. Thus, the position of the valve plates depends on the pressure differential as between inside and outside of the bucket, i.e., above and below the bottom of the bucket. As a bucket is lowered into the sea (or, more precisely, as the tube 32 pushes bottom 31 down into the water) dynamic pressure pushes the valve plates in up direction to open the valves. As essentially the entire bottom of the bucket is composed of valve structure, the bucket will fill essentially at the rate at which it is being pushed into the sea. If bottom 31 is pulled in up direction, the pressure differential reverses immediately, causing the valves to close and trapping the water which entered the bucket during the down stroke. The weight of the water in the bucket maintains the valves closed as the bucket is lifted out of the water.

We now proceed to the description of the control section 50 involving particularly the lowering and lifting of the bucket walls 33. As can be seen from FIGS. 1, 2 and 8, the two buckets which are positioned symmetrically to the roll axis proper or to the pitch axis of the barge, are controlled by two closely positioned units and may actually share components. Such a double unit is shown in FIG. 8. The control units illustrated serve particularly to control the emptying of buckets 3th.: and 30c. The linking elements are the two control cables 15a and 150 suspending bucket walls 33a and 330 respectively. The two control units operating the two cables 15a and 15c are quite similar except that one is the mirror image of the other. The pair of control units for the other control cables (15b and 15d) is constructed similar to the one illustrated.

The control cables 15a and 15c are fastened to the respective ends of control levers such as levers 51a and 51b. Lever 51a, e.g., is constructed of two registering portions respectively identified by reference numerals 511a and 512a, they are individually seated on a shaft 52a and kept in spaced apart relationship as well as in an aligned position by means of spacers 513a. The shaft 52a is supported by a cantilever bearing 521a and a gear box 522 gears the shaft 52a to a continuously running motor 523. The symmetrically positioned lever 510 is seated on a second shaft 520, likewise driven through gear box 522 by motor 523, but in opposite direction.

A ratchet wheel 53a is connected to shaft 52a to be driven continuously by the shaft. Ratchet wheel 53a is positioned in the space between the two level portions 511a and 512a. A control linking level 34a is pivotally mounted by means of a pivot 541a in between the two lever portions 512a and 5110. The control linking lever 54a has a pawl 5d2a which can engage the teeth of ratchet wheel 53a. Control linking lever 54a has a nose 5 which when engaging a stationary stop 56 can pivot lever 54a in clockwise direction (stop 56 can also pivot lever 540 in counterclockwise direction due to its central position in relation to the two levers 51a and 51b). Clockwise pivoting of lever 54a about pivot 541a permits disengagement of pawl 542a from ratchet wheel 53a.

The upper portion of lever 54la which is positioned on the opposite side with, reference to pivot point 541a, is provided with a detent cam 543a behind which can rest a nose 51a of an actuator 55a. The actuator 55d is a double-arm lever which is pivotally mounted at 552a to lever 51a, also in between the two portions 511a and 512a thereof. Actuator 55a is pivoted eccentrically in relation to its center of gravity so that normally the side with nose 551a drops. If control linkage lever 54a is caused to pivot clockwise about its pivot point 541a, nose 551a of actuator 55a rests behind detent 543a of lever 54a. In this manner lever 54a is locked in a position of disengagement from ratchet wheel 5311. Control linking lever 54a is likewise unbalanced in that as soon as actuator 55a is tripped (clockwise), lever 54a rocks counterclockwise so that its detent 543a escapes and its pawl 5d2a engages ratchet wheel 53a.

In operation, the position shown for control lever 51a corresponds to a lowermost position of bucket wall 33a, i.e., when seated on the bottom 31a in effect closing bucket 300. This is the normal position for the bucket. FIG. 8 illustrates also pawl 542a as it engages ratchet wheel 53a. Hence, actua tor 550 has just been tripped. As the ratchet wheel 53a rotates in a counterclockwise direction (with reference to the plane of the drawing) pawl 542a is forced to follow that rotation. As the control linking lever 54 is connected (at 541) to the lever 51a, and since the elements are oriented, so that the driving force exerted by ratchet 53a upon pawl 52a will not tend to pivot control linking lever 54a in a clockwise direction, lever 51a is forced to follow the rotation of ratchet wheel 53a around the axis of shaft 52a. It follows that wall 33a is thereupon lifted off the bottom 31a of bucket 30a.

As lever 51a approaches the vertical position, bucket wall 33a approaches its largest distance from bucket bottom 31a and the bucket offers the largest area of outflow obtainable by the control. As lever 51a assumes the vertical position, the nose 544a of lever 54a engages stop 56 causing pawl 5l2a to disengage from the ratchet wheel. The lever 540 in the lefthand portion of FIG. 8 is illustrated in this operating position. lts pawl 5420 disengaged from the ratchet wheel 530 while the detent 543C rests behind the nose 5510 of trip actuator 55c.

Motor 523 drives ratchet wheels 53c and 53a continuously, but as long as the respective pawl, 5 32a or 5 12c, is disengaged the rotary motion is not transmitted upon the respective control lever, 51a or 510, regardless of the position thereof. As soon as a control linking lever, e.g., 54c disengages from the respective ratchet wheel 530, (this instant is shown in FIG. 8) the respective bucket wall, 33c, as suspended from cable pulls lever 510 to pivot same in counterclockwise direction and bucket wall 330 will drop on bucket bottom 310. The operation with respect to bucket 33a as suspended from cable 15a is similar except that control lever 51a for cable 15a pivots counterclockwise for lifting bucket wall 33a, and after disengagement from ratchet 53a, lever 51a pivots clockwise under the weight of bucket wall 33a. Stops 513a and 5130 restrict pivoting of levers 51a and 510 respectively beyond an angle necessary to cause the bucket wall-to lower on the respective bucket bottom.

A lever 51 such as 51a or 51c, etc., pivots out of the vertical position after stop 56 caused decoupling from the drive and under the weight of the respective bucket wall, and 5440 or 5440, etc., disengages from stop 56 again. However, the respective pawl does not reengage the respective ratchet wheel because the respective detent 543a or 54311 remains locked behind the respective nose, 551a or 551b. Therefore, after a bucket wall has been lowered and has come to rest on the bottom of the respective bucket, the bucket is closed. A bucket remains closed until the respective trip lever, 55a or 55b, is actuated, causing the respective pawl, 542a or 54212, to reengage the respective ratchet wheel 53a or 53b. Lever 51a and pawl 542a are illustrated in FIG. 8 in that position; a driving connection for lifting is then again provided between motor 523 and the respective bucket wall as suspended by the respective control cable.

FIGS. 8 and also illustrate mechanism for providing tripping action for actuators 55a and 55c. A flat swivel tank 57 filled partially, e.g., with water is provided underneath levers 51a and 510. A baffle 571 restricts the rate of flow of water in the tank from left to right or vice versa. The two actuators 55a and 550 are respectively provided with arms 581a and Silk. Control cables 58a and 53c respectively connect the arms to opposite ends of swivel tank 57. The control cables 58a and 580 are guided over pulleys respectively 582a and 582C loosely seated on shafts 53a and 53c, respectively so that the length of the cables between swivel tank and actuator is essentially independent from the position of the respective control arm 51.

As the barge rolls about an axis perpendicular to the plane of the drawing of FIG. 8, swivel tank 57 will follow the roll, but the baffle 571 delays flow of water in direction towards the side undergoing down roll so that the imbalancing of the swivel tank is delayed close to the time of maximum roll angle. The swivel action alternates between clockwise and counterclockwise pivoting of the swivel tank. As a consequence, control cables 58a and 580 are altematingly pulled by the swivel tank to trip the respective actuator, 55a or 55c. This tripping by pulling occurs somewhat before the peak of the roll in each direction, corresponding each time to an almost completed lift of the respectively associated bucket wall. As the barge rolls in the opposite direction, the respective other one of the control cables, 58a and 580 slackens, permitting actuator 55a or 55c to drop back so its respective nose can lock behind the detent of the respective nose can lock be respective control linking lever, 540 or 540.

It will be appreciated that the simple swivel tank operation for lever tripping, as described, causes a bucket wall to lift out when having highest position. Hence, for filling a bucket the bottom thereof must have valve plates, as shown in FIG. 7, or the like. However, if a bucket has a solid bottom, the bucket wall must also be lifted at the low point of the submerged position of the bucket. In this case, tripping of the levers must occur twice per roll cycle, i.e., for each bucket whenever the roll reverses. A roll reversing sensing and operating device is disclosed, for example, in my copending application, Ser. No. 724,924, showing the development of control signals for each roll reversal, and it can readily be understood that levers 55a and 550, for example, can be tripped concurrently and briefly for each roll reversal so that filling and discharge concur for two buckets moving in phase operation.

The roll suppressing device, therefore, operates as follows: Assuming the sea to be calm and that the floating barge is level, all of the buckets are closed and partially submerged, the water level in each of the buckets is level with the surrounding sea. The respective control levers have a position as shown for lever 51a in FIG. 8, except that the noses of the respective actuators 55 latch behind the respective detents 543 of the respective control linking levers 54. Thus, none of the control levers 51 is connected to a ratchet wheel and the drive motor.

Assuming now that the barge begins to roll about any axis, then, for example, one bucket, possibly even two of the four buckets begin to lift, while the oppositely placed bucket or possibly the other two buckets will be pushed deeper into the water. A complete rolling cycle for one bucket shall be considered, beginning with a down roll of the side of the barge from which that bucket is suspended. The respective outrigger and the respective bucket suspension tube 32 pushes the bottom of the bucket down. If the bottom has valves 316, these valves 316 open and more water rushes into the bucket, possible possibly filling the bucket completely if the down stroke of the bucket as a whole is large enough. If the bottom is solid, the bucket remains empty as it is pushed down, providing antiroll torque by operation of its buoyancy. As rolling continues, the stroke reverses. The valves of the bottom close as the bucket is lifted out of the sea and the bucket remains filled with water. In case the bottom is solid, the respective actuator (55) is tripped, the associated lever (51) is coupled to the respective ratchet wheel (53) and the wall of the bucket lifts to fill the bucket. Soon the lever 51 disengages and the wall of the bucket drops to close the bucket. In either case, the closed bucket is closed after being filled as the up stroke begins. A bucket is lifted during the roll by operation of the tube 32 pulling the bottom in up direction. The relative position of bucket wall 33, cable 15 and the respective control lever 51 will not change, so that the bucket wall remains seated on the bucket bottom. At the time the roll, now in up direction, approaches the peak of that phase, the water-filled bucket has been lifted completely out of the sea, and the respective actuator 55 is tripped. if the bottom of the bucket is solid, this tripping is the second one during the roll cycle under consideration. In case the bottom of the bucket has these valve plates and assuming simple swivel tank 57 is used for lever tripping, swivel tank 57 pivots now. The amount of water in swivel tank 57 has been metered in accordance with the predominant rolling period of the barge to be ascertained empirically. Swivel tank 57, therefore, trips the respective actuator 55 pertaining to that particular bucket, and the respective control lever 51 is coupled to the respective, continuously running ratchet wheel 53. Regardless of whether or not this is first or second actuator during the roll cycle, control lever 51 begins to pull control cable 15 and the wall of the bucket is lifted off its bottom. As soon as the lifting of the bucket wall begins, water is discharged from the bucket. The rate of outflow of the water increases due to the rapidly enlarging cross section of permissible outflow between wall and bottom.

Buckets should be opened in this manner so that all of the water has been discharged before the down phase of the roll begins again. On the other hand, the bucket should stay filled as long as possible to provide maximum counter momentum during most of the up stroke. Thus, the bucket wall should lift rather rapidly from the bottom to permit bucket discharge in a very short period of time. As a control lever 51 reaches vertical position it decouples from the respective drive 523 and the bucket is closed again. The roll again reverses its phase and the empty bucket is lowered to be filled again. As long as the roll persists the bucket will thus alternate between dipping into the sea and refilling, and subsequent lifting and dischargmg.

The operation, therefore, is such that during a lifting phase of a bucket, due to rolling of the barge, the bucket should remain full as long as that lifting motion is maintained in order to provide a roll damping, maximum counter momentum. The oppositely positioned bucket undergoes concurrently a down stroke; it is empty or in the state of filling through opened bottom valves. That bucket does not exert any additional weight onto the respective outrigger from which it is suspended. Therefore, during a particular rolling phase, the two buckets which are symmetrically positioned to the roll axis, exert asymmetric forces upon the two respective diametrically opposed outriggers. As a consequence, roll damping momentum is in effect developed in relation to that axis. As the roll reverses, the direction of the roll damping momentum reverses likewise as the previous empty bucket is now filled, while the other one has been emptied in the meantime.

it is an essential feature of the inventive device that the roll damping or suppressing momentum is not developed by a closed system: Mass needed for developing the momentum is admitted to the system when needed and discharged therefrom after having fulfilled its function, i.e., that mass (water in buckets) enters and leaves the system as required whereby admittance and discharge are essentially controlled by the roll itself. The timing of admittance and discharge of the roll damping mass is critical for effective operation, but the system is designed in that the roll cycle determines this timing itself.

A barge moored to an offshorelocation in the ocean and provided with four orthogonally arranged pairs of buckets, as shown in FIG. 1, is, therefore, equipped to suppress roll about their axes of symmetry and independent from the operation of the other pair of buckets, so that the orthogonal system of two independently operating pairs of buckets can damp roll about any axis, even if that axis varies position. In other words, roll proper and pitch are damped or suppressed independently.

The roll damping system is controlled to be effective independent from the actual roll period. The trigger control for the buckets as disclosed (swivel tank 57) is a very simple device. Alternative constructions are well possible or levers 55a, 55b etc., etc., may even be triggered manually. The trip control of actuator 55 is shown as a mechanical device, but could be used controlling, for example, electromagnetic actuators. Still alternatively, one could substitute the control cables such as th: and 5% by solenoids actuating the respective trip actuators 58a and 58c.

As shown in FIGS. and 3a, there are provided solenoids such as 115 for lifting the bottom 134 from seats on the lower portion of a streamlined sidewall 133 of a bucket 130 for opening the bucket. Alternatively, the bottom could be operated by the solenoid 1115 to be pushed down for opening of the bucket, while maintained in abutment with the lower ridge of the wall from below. The solenoids are actuated at the time of the peak of the roll in either direction. The solenoids could be controlled by switches closed and opened by the swivel tank 57, or a damped pendulum, or a gyroscope. A preferred control device for such operation is disclosed in my copending application, Ser. No. 724,924. Still alternatively, one could provide electromagnetic clutches to couple cables 15 to drive 523.

Another point to be considered is that for separating the wall from the bottom of a bucket, the bottom could be pushed down leaving the wall in rigid suspension while pushing the bottom down for filling as well as discharging.

The system as described can also be called an active system because the duration of the roll damping momentum is a controlled operation; the buckets are maintained tilled in a timed manner and emptied in controlled synchronism with the roll. A more simplified system can be established if one considers the active system as disclosed to be maintained in a particular, fixed operating state. This may become necessary, for example, if the bucket-emptying control Stl is not operating, needs repair, etc. The essential characteristic of the control is the sensing of the approach of maximum lift of a bucket and causing its discharge. Such a discharge must be as late as permissible but not later than appropriate, so that the bucket is empty at the peak lift. The bucket wall 33 is maintained in a predetermined distance above the bottom, i.e., levers 511, may be assumed to be arrested in an in-between position in relation to the ones shown in FIG. 5. in other words, the buckets are provided with a permanently open construction permitting outflow of water whenever the bucket is lifted. The bucket will fill through the same gap between bottom and permanently lifted wall, and/or through the valves as aforedescribed. For a permanently passive system the valves may be omitted entirely. For a temporarily passive system the valves may be latched to remain closed if and as long as the normally active system operates in the passive mode. As the bucket is lifted, water will pour out. This begins as soon as the roll movement reverses direction. However, the permanently open construction of the bucket, such as a permanent gap between wall and bottom there, must be restricted, so that the outpour is slower than the rate of lifting in accordance with the usual roll period. Thus, the bucket still contains substantial amounts of water at a time when the bottom also lifts out of the water. On the other hand, the aperture, for example, the gap between wall 33 and bottom 31, has to be dimensioned so that water has been discharged by the time the bucket reaches maximum height.

Such a passive system is, of course, not as effective as the active one, because in the active system the entire content of the filled bucket is available for developing a roll damping momentum of essentially constant amplitude throughout most of the up stroke phase of a roll cycle and just-about until the peak position has been reached. The passive system requires the continuous discharge to be completed at the end of an up stroke phase of a roll cycle, so that on the average, only about half of the maximum momentum is available. it is apparent, however, that by operation of this device, active or passive, the rolling motion can be damped substantially so that the residual roll amplitude is small in comparison with roll amplitudes occurring without the clamping device.

If the roll suppressing device is not to be used at all for any reason, then, as can be seen from FIG. 3, A-frames 21 will be folded up to be maintained in vertical position; the bracing cables 27, 25 and 26, of course, have to be removed or loosened. The outriggers can be lifted by winch l3 hoisting A-frames 20 through the respective suspension cables 12 to fold the A- frames in up direction.

The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.

lclaim:

l. A stabilizing and roll damping device for floating marine structures, comprising:

a pair of outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll;

a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats and in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during rolling in phase opposition;

closeable aperture defining means in each of the buckets for selectively admitting water to the respective bucket as the bottom thereof moves below the water line due to downstroke roll and discharging water therefrom into surrounding water wherein the structure floats; and

means coupled to the closeable aperture defining means for controlling outflow of water in timed relation to each upstroke of the respective bucket, so that the bucket is at least partially full during at least most of the upstroke while being empty at least shortly after reversal to downstroke until being refilled upon becoming submerged in the respective later portion of each downstroke.

2. Device as set forth in claim 1, including means coupled to the closeable aperture defining means for controlling inflow of water in a bucket of the pair in synchronism with outflow of the respective other bucket of the pair.

3. A stabilizing and roll damping device for floating marine structures, comprising:

a pair of outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll;

a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats, and in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during the rolling in phase opposition;

means included in the buckets causing the buckets to be filled during each respective downstroke phase of a bucket of the buckets essentially at the rate of submerging; and

means coupled to the buckets to provide controlled outflow of a bucket of the buckets to discharge water therefrom into the water wherein the structure floats and in timed relation to upstroke and downstroke so that the respective bucket contains at least a substantial amount of water during an upstroke phase as the filled bucket lifts out of the water, while remaining at least substantially empty at downstroke prior to submergence.

4. Device as set forth in claim 3, the means included in the buckets comprising valve means in the bottoms of the buckets.

5. A stabilizing and roll damping device for floating marine structures, comprising:

an outrigger disposed on one side of the structure and extending therefrom;

a bucket suspended by and from the outrigger for submerging into and lifting out of the water in which the structure floats, in alternating downstroke and upstroke phases during roll of the structure about an axis transverse to the direction of extension of the outriggers;

first means at the bucket for enabling inflow of surrounding water into the bucket when the bucket is at least partially submerged during a downstroke phase, and for disabling complete outflow of water from the bucket during each upstroke phase, prior to complete lifting of the bucket from the water surface as the structure rolls; and

second means operatively connected to the first means for controlling the means as to the timing of inflow and outflow such that the bucket being at least substantially empty during a downstroke phase subsequent to a lifting and prior to new inflow during such downstroke phase.

6. Device as set forth in claim 5, the second means operating the first means to maintain the bucket empty up to about reversal from downstroke to upstroke, and to empty the bucket at about reversal from upstroke to downstroke.

7. A device as set forth in claim 5, the bucket comprising a bottom and a vertically movable wall structure, the bottom being suspended from the outrigger and following the roll thereof during roll of the marine structure; the device further including means for suspending the cylindrical wall of the bucket, and means for providing controlled motion of the wall for selectively seating the wall on the bottom and lifting it therefrom.

8. A device as set forth in claim 7, wherein said bottom is provided with valve means operable upon submerging motion of the bottom into the water.

9. A device as set forth in claim 5, the means including means for inhibiting outflow of water from the bucket during at least most of the up phase of the bucket when being lifted pursuant to roll of the structure, while causing discharge of water in the bucket to commence prior to the downstroke of a bucket.

1.0. A device as set forth in claim 5, including means for sensing the approach of the maximum lift stroke of a bucket to control the discharge of water in the bucket.

11. A device as set forth in claim 5, including means for sensing the opposite of maximum downstroke of a bucket to control opening the bucket for inflow of water.

12. A stabilizing, roll clamping device for floating marine structures, comprising:

a pair of outriggers oppositely disposed on the structure in symmetric relation to the axis of the structure about which rolling may occur;

a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats in alternating phases during roll of the structure about the axis, the buckets lifting and lowering during the rolling in phase opposition;

the buckets constructed to have separable wall and bottom;

and

means for controlling temporary separation of a wall of a bucket of the pair subsequent to each lifting of the bucket from the water for discharge of the water lifted by the bucket.

13. A device as set forth in claim 12, and including means for controlling temporary separation of the wall of a bucket of the pair at about the time of reversal from downstroke to upstroke, the wall being on the bottom during submergence of the bucket in the downstroke phase when the bucket is empty, and again in the subsequent upstroke phase when the bucket is full.

14. A device as set forth in claim 12, the means for controlling providing relative lift of a wall of the walls from the respective bottom at about reversal from upstroke to downstroke.

15. A device as set forth in claim 12, the means for controlling providing additional separation of the walls at about reversal from upstroke to downstroke.

16. A device as set forth in claim 12, the walls ofthe buckets being streamlined in direction of the axis of symmetry.

17, A device as set forth in claim 12, the walls ofa bucket of the buckets being separable from the respective bottom by means of a piston,

18. A device as set forth in claim 12, the buckets being suspended by means for pushing at least the respective bottom of each bucket into the water and against any buoyancy thereof.

19. A device as set forth in claim 12, the walls of a bucket of the buckets being suspended from the respective outrigger, the bottom of the bucket being movable relative to the wall under control of the means for controlling.

20. A stabilizing, roll damping device for floating marine structures, comprising:

a pair of outriggers oppositely disposed on the structure in symmetric relation to the axis of the structure about which rolling may occur;

a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats in alternating phases during roll of the structure about the axis, the buckets lifting and lowering during the rolling in phase opposition;

closeable aperture defining means in each of the buckets for admitting water to a bucket of the buckets when partially or completely submerged and for causing controlled discharge of water from a bucket into the water in which the structure floats after the full or partially filled bucket has been lifted above the water surface; and

means operating the closeable aperture defining means of each bucket ofa pair to open the buckets at least approximately at time of roll reversal, a bucket of the pair to remain closed in that the respective aperture defining means is closed essentially throughout the upstroke when the bucket is filled, and during the downstroke when the empty bucket dips into the water.

21. A stabilizing and roll damping device for floating marine structures, comprising:

a pair of outriggers disposed opposite sides of the structure in relation to an axis of the structure about which the structure may roll;

a pair of buckets each having wall and bottom structure, the wall structure of a bucket of the pair respectively seated on the bottom structure thereof;

means for coupling the bottom structures of the buckets respectively to the outriggers, so that a bottom structure of the bottom structures is pushed into the water in which the marine structure floats as the respective other bottom structure is lifted during rolling of the marine structure about the axis, the bottom structures of the pair being accordingly lifted and lowered in phase opposition; and

means for suspending the wall structures to be seated on the respective bottom structures during at least most of an upstroke and empty at least during most of the downstroke prior to refilling of the bucket upon submer gence of its bottom structure during downstroke.

22. A stabilizing and roll damping device for floating marine structures, comprising:

a pair of Outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll;

a pair of. buckets respectively suspended by and from the Outriggers for submerging into and lifting out of the water in which the structurefloats, in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during the rolling in phase opposition; and

means responsive to rolling motion of the structure about the axis and controlling opening and closing of the buckets for causing the buckets to be filled when fully or partially submerged by direct inflow of water, surrounding the bucket during a downstroke thereof while providing delayed complete outflow of water from the respective bucket when lifted from the water surface during a succeeding upstroke, so that the respective bucket lifts from the water surface at least some of the water which flowed in, while during the respectively succeeding downstroke the bucketis at least substantially empty prior to refilling during such downstroke.

23. A device as set forth in claim 22, the rolling motion responsive means controlling the buckets for opening at about the time highest upstroke.

24. A device as set forth in claim 22, the rolling motion responsive means controlling the buckets for opening each of them at about time of reversal of direction of the rolling motion. 

1. A stabilizing and roll damping device for floating marine structures, comprising: a pair of outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll; a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats and in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during rolling in phase opposition; closeable aperture defining means in each of the buckets for selectively admitting water to the respective bucket as the bottom thereof moves below the water line due to downstroke roll and discharging water therefrom into surrounding water wherein the structure floats; and means coupled to the closeable aperture defining means for controlling outflow of water in timed relation to each upstroke of the respective bucket, so that the bucket is at least partially full during at least most of the upstroke while being empty at least shortly after reversal to downstroke until being refilled upon becoming submerged in the respective later portion of each downstroke.
 2. Device as set forth in claim 1, including means coupled to the closeable aperture defining means for controlling inflow of water in a bucket of the pair in synchronism with outflow of the respective other bucket of the pair.
 3. A stabilizing and roll damping device for floating marine structures, comprising: a pair of outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll; a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats, and in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during the rolling in phase opposition; means included in the buckets causing the buckets to be filled during each respective downstroke phase of a bucket of the buckets essentially at the rate of submerging; and means coupled to the buckets to provide controlled outflow of a bucket of the buckets to discharge water therefrom into the water wherein the structure floats and in timed relation to upstroke and downstroke so that the respective bucket contains at least a substantial amount of water during an upstroke phase as the filled bucket lifts out of the water, while remaining at least substantially empty at downstroke prior to submergence.
 4. Device as set forth in claim 3, the means included in the buckets comprising valve means in the bottoms of the buckets.
 5. A stabilizing and roll damping device for floating marine structures, comprising: an outrigger disposed on one side of the structure and extending therefrom; a bucket suspended by and from the outrigger for submerging into and lifting out of the water in which the structure floats, in alternating downstroke and upstroke phases during roll of the structure about an axis transverse to the direction of extension of the outriggers; first means at the bucket for enabling inflow of surrounding water into the bucket when the bucket is at least partially submerged during a downstroke phase, and for disabling complete outflow of water from the bucket during each upstroke phase, prior to complete lifting of the bucket from the water surface as the structure rolls; and second means operatively connected to the first means for controlling the means as to the timing of inflow and outflow such that the bucket being at least substantially empty during a downstroke phase subsequent to a lifting and prior to new inflow during such downstroke phase.
 6. Device as set forth in claim 5, the second means operating the first means to maintain the bucket empty up to about reversal from downstroke to upstroke, and to empty the bucket at about reversal from upstroke to downstroke.
 7. A device as set forth in claim 5, the bucket comprising a bottom and a vertically movable wall structure, the bottom being suspended from the outrigger and following the roll thereof during roll of the marine structure; the device further including means for suspending the cylindrical wall of the bucket, and means for providing controlled motion of the wall for selectively seating the wall on the bottom and lifting it therefrom.
 8. A device as set forth in claim 7, wherein said bottom is provided with valve means operable upon submerging motion of the bottom into the water.
 9. A device as set forth in claim 5, the means including means for inhibiting outflow of water from the bucket during at least most of the up phase of the bucket when being lifted pursuant to roll of the structure, while causing discharge of water in the bucket to commence prior to the downstroke of a bucket.
 10. A device as set forth in claim 5, including means for sensing the approach of the maximum lift stroke of a bucket to control the discharge of water in the bucket.
 11. A device as set forth in claim 5, including means for sensing the opposite of maximum dOwnstroke of a bucket to control opening the bucket for inflow of water.
 12. A stabilizing, roll damping device for floating marine structures, comprising: a pair of outriggers oppositely disposed on the structure in symmetric relation to the axis of the structure about which rolling may occur; a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats in alternating phases during roll of the structure about the axis, the buckets lifting and lowering during the rolling in phase opposition; the buckets constructed to have separable wall and bottom; and means for controlling temporary separation of a wall of a bucket of the pair subsequent to each lifting of the bucket from the water for discharge of the water lifted by the bucket.
 13. A device as set forth in claim 12, and including means for controlling temporary separation of the wall of a bucket of the pair at about the time of reversal from downstroke to upstroke, the wall being on the bottom during submergence of the bucket in the downstroke phase when the bucket is empty, and again in the subsequent upstroke phase when the bucket is full.
 14. A device as set forth in claim 12, the means for controlling providing relative lift of a wall of the walls from the respective bottom at about reversal from upstroke to downstroke.
 15. A device as set forth in claim 12, the means for controlling providing additional separation of the walls at about reversal from upstroke to downstroke.
 16. A device as set forth in claim 12, the walls of the buckets being streamlined in direction of the axis of symmetry.
 17. A device as set forth in claim 12, the walls of a bucket of the buckets being separable from the respective bottom by means of a piston.
 18. A device as set forth in claim 12, the buckets being suspended by means for pushing at least the respective bottom of each bucket into the water and against any buoyancy thereof.
 19. A device as set forth in claim 12, the walls of a bucket of the buckets being suspended from the respective outrigger, the bottom of the bucket being movable relative to the wall under control of the means for controlling.
 20. A stabilizing, roll damping device for floating marine structures, comprising: a pair of outriggers oppositely disposed on the structure in symmetric relation to the axis of the structure about which rolling may occur; a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats in alternating phases during roll of the structure about the axis, the buckets lifting and lowering during the rolling in phase opposition; closeable aperture defining means in each of the buckets for admitting water to a bucket of the buckets when partially or completely submerged and for causing controlled discharge of water from a bucket into the water in which the structure floats after the full or partially filled bucket has been lifted above the water surface; and means operating the closeable aperture defining means of each bucket of a pair to open the buckets at least approximately at time of roll reversal, a bucket of the pair to remain closed in that the respective aperture defining means is closed essentially throughout the upstroke when the bucket is filled, and during the downstroke when the empty bucket dips into the water.
 21. A stabilizing and roll damping device for floating marine structures, comprising: a pair of outriggers disposed opposite sides of the structure in relation to an axis of the structure about which the structure may roll; a pair of buckets each having wall and bottom structure, the wall structure of a bucket of the pair respectively seated on the bottom structure thereof; means for coupling the bottom structures of the buckets respectively to the outriggers, so that a bottom structure of the bottom struCtures is pushed into the water in which the marine structure floats as the respective other bottom structure is lifted during rolling of the marine structure about the axis, the bottom structures of the pair being accordingly lifted and lowered in phase opposition; and means for suspending the wall structures to be seated on the respective bottom structures during at least most of an upstroke and empty at least during most of the downstroke prior to refilling of the bucket upon submergence of its bottom structure during downstroke.
 22. A stabilizing and roll damping device for floating marine structures, comprising: a pair of outriggers disposed on opposite sides of the structure in relation to an axis of the structure about which the structure may roll; a pair of buckets respectively suspended by and from the outriggers for submerging into and lifting out of the water in which the structure floats, in alternating phases of upstroke and downstroke during rolling of the structure about the axis, the buckets of the pair lifting and lowering during the rolling in phase opposition; and means responsive to rolling motion of the structure about the axis and controlling opening and closing of the buckets for causing the buckets to be filled when fully or partially submerged by direct inflow of water, surrounding the bucket during a downstroke thereof while providing delayed complete outflow of water from the respective bucket when lifted from the water surface during a succeeding upstroke, so that the respective bucket lifts from the water surface at least some of the water which flowed in, while during the respectively succeeding downstroke the bucket is at least substantially empty prior to refilling during such downstroke.
 23. A device as set forth in claim 22, the rolling motion responsive means controlling the buckets for opening at about the time highest upstroke.
 24. A device as set forth in claim 22, the rolling motion responsive means controlling the buckets for opening each of them at about time of reversal of direction of the rolling motion. 